ŻARNOWIEC Hydroelectric Power Plant

Transcription

1 ŻARNOWIEC Hydroelectric Power Plant turbining regime 4 x 179 (195) MW pumping regime 4 x (179 to 198) MW

2 start-up motor generator thrust bearing 4.24 m below mean sea level 8.66 m below mean sea level m below mean sea level pump-turbine guide bearing EW ŻARNOWIEC hydraulic units GENERATOR Elektrotiazhmash, Kharkov, USSR type: CBO-117/19-36 apparent power: 29/228 MVA PUMP-TURBINE CKD Blansko, Czechoslovakia runner type: FR 25.6 Ø 571 Ø 6 Ø m below mean sea level 21.5 m below mean sea level rated power of the unit: 179 MW (turbining mode) 198 MW (pumping mode) static head: 18 to 12 m rotation speed: r.p.m.

3 EW ŻARNOWIEC original units operating range

4 mechanical efficiency [%] EW ŻARNOWIEC efficiency gains expected in the turbining regime SULZER Hydro offer (March 21) Unit no.3 (March 21) EW ŻARNOWIEC turbining regime H = 12 m power on the shaft [MW]

5 EW ŻARNOWIEC refurbishment scope of unit no.2 replacement of the runner modification of the guide vanes profile and replacement of their bearing system rewinding of the generator contract December 1999 commissioning November 2 / January 21 acceptance tests March 21

6 ON EXPERIENCE FOLLOWING FROM COMMISSIONING TESTS OF A PUMP/TURBINE AFTER RUNNER REPLACEMENT Adam Adamkowski, Janusz Steller Polish Academy of Sciences, Institute of Fluid-Flow Machinery, Gdansk, Poland Tadeusz Kiedrowski Pumped Storage Power Plants Co., Czymanowo, Poland load rejection tests in the turbining mode of operation start-up to the pumping mode of operation relief of the pump/turbine runner axial thrust

7 wicket gate opening, Y[%] pressure in the penstock [kpa] rotation speed n/n o [%] wicket gate opening Y k [%] LOAD REJECTION TESTS IN THE TURBINING MODE OF OPERATION 1 8 wicket gate opening, Y [%] k s 5.2 s 7.s 53.8 s 47.2 s WICKET GATE OPENING/CLOSING LAW DURING A STILLSTAND THE STATE PRIOR TO THE REFURBISHMENT wicket gate closing prior to the refurbishment wicket gate closing law after modification time [s] 8 6 n = rpm Initial conditions P = 15. MW Q = m 3 /s s 62.9 s 6.9s 74.9 s 66.6 s Initial conditions P = MW Q = m 3 /s WICKET GATE OPENING/CLOSING LAW DURING A STILLSTAND; MODIFIED (LINEAR) LAW time [s] time [s]

8 LOAD REJECTION TESTS IN THE TURBINING MODE OF OPERATION wicket gate opening, Y k [%] pressure in the penstock, kpa rotation speed n/n o [%] modified wicket gate closing law n = obr/min with closed interconnection P = 192. MW Q = 19.5 m 3 /s with open interconnection P = MW Q = m 3 /s time [s]

9 wicket gate & valve opening [%] pressure [kpa] power P/P o [%] valve opening wicket gate opening n = rpm P = MW Ø 115 orifice Ø 15 orifice after runner cone refurbishment Ø 15 orifice penstock START-UP TO THE PUMPING MODE OF OPERATION PROBLEMS ENCOUNTERED insufficient de-aeration of of the runner chamber REASONS IDENTIFIED alterations in the runner cone design (improper situation of the thrust-relief holes) leakage through the closed wicket gates REMEDIES APPLIED decrease of leakage by delaying the inlet valve opening process vaneless space WDPF measurement intensification of the runner chamber de-aeration process by increasing the orifice diameter in the de-aeration pipe redesign of the runner cone time [s]

10 AXIAL THRUST RELIEF PROBLEMS segment no MPa 185 MW 91 MW segment no. 1 1 MPa February November 2 5 May 2 H = 12 m 7 pressure over segments H total = 121 m 7 pressure over segments January 2nd, 21: failure of the thrust bearing in result of an excessive axial thrust Remedies taken: redesign of the pump/turbine runner cone, reduction of the clearance between the runner hub and the upper guide wheel ring

11 AXIAL THRUST RELIEF BY MEANS OF THE DESIGN MEASURES turbine cover 27 turbine cover runner 14 runner effective relief by applying additional holes and a labyrinth sealing ineffective relief due to the centrifugal force and throttling effects 2 redesign original design

12 ciśnienie [kpa] ASSESSMENT OF THE AXIAL THRUST RELIEF EFFECTS - MEASUREMENT RESULTS in the vaneless space 9 8 upstream the internal labyrinth TURBINING MODE pressure under the runner cover and in the vaneless space 1 pressure in the vaneless space 5 4 under the cover outer diameter 2 pressure upstream the internal labyrinth 3, 4 pressure under the runner cover Institute of Fluid-Flow Machinery of the Polish Academy of Sciences 3 2 under the cover inner diameter P [MW]

13 pressure over the runner [MPa] ASSESSMENT OF THE AXIAL THRUST RELIEF EFFECTS TURBINING REGIME pressure distribution over the pump/turbine runner H total = 12.5 m P=91 MW P=172 MW distance from the runner axis [mm] F o F m g Q ρ g F d F pg mg QV F s pd i p pi mass of all the rotating components of the unit, acceleration of gravity, volumetric flow rate, density of water, A V s = Q/A s average water velocity in the outflow cross section of the draft tube cone, A s pi p surface area of the outflow cross section of the draft tube cone, ΔA pi = πd i ΔD i /2 surface area of an elementary p pump/turbine runner ring subject to p pi pressure, p p p s pressure beneath the pump/turbine head cover (over the runner), pressure in the draft tube cone, s A s

14 CONCLUSION 1. Basing on the numerical calculation and emergency load rejection tests, the wicket gates closing law has been changed in a manner allowing to avoid threats to the penstock and to keep the momentary overspeed within the allowable range. 2. The difficulties encountered at starting the machine to pumping operation after runner replacement - related initially with lack of possibility to deaerate the runner chamber and the draft tube cone and then with improper course of this process - have been removed by introducing a new control procedure and design modifications in the de-aerating pipe. 3. The excessive axial thrust of the new pump/turbine runner, which resulted in a thrust bearing failure of a newly refurbished unit, has been substantially reduced by introducing design modifications in the runner cone (mainly, by applying additional thrust relief holes) and by reducing the clearance between the runner and the guide ring